Method of producing maleic anhydride

Abstract

A method of producing maleic anhydride by oxidizing a hydrocarbon material selected from unsaturated hydrocarbons having four or more of carbon atoms, butane and mixtures thereof with molecular oxygen or a molecular oxygen containing gas in gaseous phase and in the presence of a catalyst. The catalyst used in this method is of the type which contains vanadium, phosphorus, potassium and iron, and these components are contained in the following ratios per atom of vanadium: phosphorus, 2/3 to 140 atoms; potassium, 1/4 to 2 atoms; and iron, 1/10 to 70 atoms. Preferably the atomic ratio of phosphorus/iron is greater than 1.

What is claimed is: 
     
       1. A method of producing maleic anhydride by oxidizing a hydrocarbon material selected from unsaturated hydrocarbons having four or more carbon atoms, butane and mixtures thereof with molecular oxygen or a gas containing molecular oxygen in a gaseous phase and in the presence of a catalyst, characterized in that the catalyst used here contains vanadium, phosphorus, potassium and iron in the form of oxides, with these ingredients being contained in the following atomic ratios calculated per atom of vanadium: phosphorus, 2/3 to 140 atoms; potassium, 1/4 to 2 atoms; and iron, 1/10 to 70 atoms. 
     
     
       2. A method according to claim 1, wherein the hydrocarbon material is unsaturated hydrocarbons having four or more carbon atoms. 
     
     
       3. A method according to claim 1, wherein the hydrocarbon material is butane. 
     
     
       4. A method according to claim 1, wherein the reaction is carried out at such a rate that the hydrocarbon concentration will be within the range of 0.5 to 10 vol %. 
     
     
       5. A method according to claim 1, wherein the reaction is carried out at the temperature of 300° to 600° C. 
     
     
       6. A method according to claim 1, wherein the atomic ratio of phosphorus/iron in the catalyst is greater than 1.